Packaging machines have heretofore been made for example as shown in U.S. Pat. Nos. 2,612,016; 3,206,915; 3,364,651 and 3,466,838 for packaging material in rectangular cartons which are initially supplied in a flattened condition and have four body panels interconnected along fold lines to form a rectangular body and closure flaps interconnected along fold lines to the four body panels for closing ends of the carton. In general, the packaging machines disclosed in the aforementioned patents are arranged to open and erect carton blanks at a carton infeed station and have a transfer mechanism mounted for extension and retraction along a path and operative when driven through a transfer cycle to advance a series of cartons in step fashion from the infeed station sequentially past a lower carton closing station; a filling station; and an upper carton closing station. In these packaging machines, product is dispensed in continuous fashion through a downwardly opening nozzle at the filling station and an elevator at the filling station is operated in timed relation with the transfer mechanism to elevate a carton into partial telescoping relation with the nozzle and then allow the carton to move down as it is filled. When the carton at the filling station reaches a preselected lower position, a transfer cycle is initiated to advance the series of cartons along the path in a forward step. Such packaging machines are herein referred to as intermittently cycled packaging machines.
Some prior intermittently cycled packaging machines such as disclosed in U.S. Pat. Nos. 2,612,016 and 3,364,651 are adapted to handle cartons having mechanically interlocking end flaps on the narrow side panels of the cartons and such machines were arranged to first infold the end flaps on the wide panels of the carton and then infold and interlock the end flaps on the narrow side panels. U.S. Pat. No. 3,206,915 also discloses an intermittently cycled packaging machine adapted for handling cartons having mechanical interlocking end flaps, and this patent further discloses an adhesive applying attachment at the outlet end of the packaging machine to adapt the machine to handle chest-type cartons that have, in addition to the mechanical interlocking end flaps, a tab at each end of the cover flange which is adpated to be secured to an end flap on an adjacent side panel of the carton. The adhesive applying attachment in U.S. Pat. No. 3,206,915 was arranged to move the filled and closed cartons crosswise of the outlet end of the packaging machine; apply a spot of glue to the top and bottoms of the cartons while the cartons were at rest; and then advance the cartons past upper and lower plows that folded the end tabs onto the glue spots. Some other intermittently cycled packaging machines such as shown in U.S. Pat. No. 3,466,838 are arranged to erect, fill, close, and heat seal cartons having pre-glued end flaps, with heat sealers arranged to heat the pre-glued end flaps after both ends of the carton were closed and while the cartons were at rest during a dwell period between transfer cycles.
U.S. Pat. No. 4,239,115 discloses a carton construction adapted to have the end flaps closed and sealed with hot melt adhesive when the end flaps are folded in a particular sequence and the adhesive is applied in a particular adhesive pattern. More specifically, the carton in this patent has the end flap on one wide side panel dimensioned so that, when infolded last, it overlaps portions of the other three end flaps, and closing of the carton is effected by sequentially infolding the end flaps on the two narrow side panels; infolding the end flap on the other wide side panel; applying hot melt adhesive on the infolded end flaps in bands paralleling the narrow side panels, and then infolding the end flap on the first mentioned wide side panel.
The adaptation of intermittently cycled packaging machines of the type described above to the closing and sealing of such cartons with hot melt adhesive has presented various problems. Such packaging machines have a dwell period between each transfer cycle to allow time for dispensing the required quantity of product from the nozzle into the carton at the fill station. The dwell period of the machine will vary dependent on the rate to which the product is dispensed from the nozzle into the cartons, and the glue application and flap folding should be so arranged that reliable sealing is effected independent of variations in the packaging machine fill time. Further, since the product is dispensed continuously from the nozzle on the packaging machine, it is desirable to advance the carton past the nozzle with the wide side panels of the carton transverse to the path of movement of the carton, in order to minimize the amount of material that flows from the nozzle during movement of the filled carton away from the nozzle and the next empty carton into position below the nozzle. The glue application and flap folding must therefore also be arranged so that it will apply adhesive in the proper pattern on the infolded end flaps on the carton and rapidly fold the final end flap onto the adhesive, when the carton is oriented with the wide side panels extending crosswise of the path of advance of the cartons in the packaging machine. Further, the lower flap folding and adhesive applying mechanism must be capable of closing the lower ends of the cartons when they are empty while the upper flap folding and adhesive applying mechanism must be capable of closing the cartons when they are filled. Closing and sealing the upper end of the cartons has presented special problems due in part to the necessity of outfolding the upper flaps to enable filling, and in part to bulging of the carton by the product when it is filled.